Alkali soluble rayon textile material and process for producing same

ABSTRACT

ALKALI SOLUBLE TEXTILE MATERIAL PRODUCED WITHOUT RESORTING TO A CARBOXYMETHYLATION STEP BY THE IMPREGNATION OF RAYON WITH AN AQUEOUS SOLUTION OF CHROMIC ACID OR ERIODIC ACID, THE RESULTANT MATERIAL BEING HIGHLY SOLUBLE IN ALKALINE DISSOLVING BATHS, SUCH SOLUTION BEING FREE OF GUMMY RESIDUES.

United States Patent Office 3,824,078 ALKALI SOLUBLE RAYON TEXTILEMATERIAL AND PROCESS FOR PRODUCING SAME Daniel J. Egan, New Foundland,N.J., assignor to Londat Aetz Fabric C0., Elizabeth, NJ. No Drawing.Filed Nov. 8, 1971, Ser. No. 196,780 Int. Cl. D06m 11/02 US. Cl. 8-120 8Claims ABSTRACT OF THE DISCLOSURE Alkali soluble textile materialsproduced without resorting to a carboxymethylation step by theimpregnation of rayon with an aqueous solution of chromic acid orperiodic acid, the resultant material being highly soluble in alkalinedissolving baths, such solution being free of gummy residues.

BACKGROUND- OF THE INVENTION In Pat. No. 2,921,934, issued Jan. 19, 1960there is disclosed a procedure for converting cotton textile materialsto alkaline soluble form by initially treating the cotton with suitablereagents to convert the same to carboxymethyl cellulose. Thecarboxymethylcellulose is then impregnated with a solution of chromicacid or periodic acid. The resultant acid treated material shows goodsolubility in alkaline dissolving baths and is free of gummy residueswhich are highly undesirable, particularly when the acid treatedmaterial is used as a backing for making lace, or in other textileproducts.

.However, the preliminary treatment of the cotton fabric or thread toconvert the same to carboxyntethyl cellulose represents a substantialcost factor in the finished material; taking into account the cost ofthe necessary chemicals and the increased labor, time and equipmentrequired for the initial conversion step.

\Accordingly, an object of this invention is to provide an improvedprocess for making alkaline soluble textile materials, wherein rayonfabric or threads are directly treated with an aqueous solution ofchromic acid or periodic acid; the acid treated material being highlysoluble in alkaline dissolving baths and free from undesirable gummyresidues.

Another object of this invention is to provide a process of thecharacter described wherein rayon fabrics of fine texture are convertedto alkaline soluble form; such converted fabrics retaining substantiallytheir original texture and strength thereby facilitating lace makingoperations wherein the converted fabric provides backing means in thelace making procedure. 3

Another object of this invention is to provide an improved alkalinesoluble fabric derived from rayon of selected textures and qualities,with minimal manufacturing costs of the same by reason of the simplifiedchemical treating procedures involved; the treated fabric retainingsubstantially its original texture and strength so as to be particularlyuseful in the art of lace making.

Still another object of this invention is to provide an improvedchemical treating procedure to rayon, whether made by the cuprammoniunr,xanthate or saponified cellulose acetate process, to produce a materialwhich is highly soluble in alkaline dissolving baths; the acid of thetreating procedure leaving the original physical form of the rayonunchanged with a retention of a substantial portion of the tensilestrength of the untreated rayon.

Other objects of this invention will in part be obvious and in parthereinafter pointed out.

DESCRIPTION OF THE PREFERRED EMBODIMENTS It has been found that rayonfabrics of varying textures may be readily converted to an alkalinesoluble form,

3,824,078 Patented July 16, 1974 by direct treatment or impregnation ofthe fabric with chromic acid or periodic acid. Upon correlating acidconcentrations, temperatures and impregnation intervals, the acidtreated fabric will retain substantially its original strength andtexture. Further such acid treated fabrics will be highly soluble inalkaline dissolving baths such as aqueous solutions of sodium hydroxideor the like. 1

The following examples illustrate the invention:

Example 1 EA woven Bemberg rayon fabric of a 76 x 76 thread count, wassoaked for 90 seconds at C. in an aqueous impregnating solutioncontaining by weight 3% sodium bichromate and 4% concentrated sulfuricacid.

The acid treated fabric was then removed from the impregnating solutionand washed with water. The washed fabric was dried and showedsubstantially the tensile strength and texture of the original fabric.The acid treated fabric was then placed in a boiling 10% aqueoussolution of sodium hydroxide, by weight. The acid treated fabricdissolved rapidly. On filtering and weighing a small non-gummy residue,the solubility of the converted fabric in the sodium hydroxide solutionwas calculated as 99.4%.

The foregoing procedure was repeated except that the Bemberg rayonfabric was replaced by a viscose rayon fabric. The acid treated materialshowed a high solubility in a sodium hydroxide bath and no gummyresidue.

Example 2 Bright, non-pigmented rayon yarn derived from saponifiedcellulose acetate, was soaked in a 4% aqueous solution of chromic acid,by weight, for 90 seconds at 75 C. The acid treated yarn was then washedand dried. On placing the acid treated yarn in a boiling bath of 91%aqueous sodium hydroxide, by weight, the same showed a solubility of98.9% and with no gummy residue. The acid treated yarn retainedsubstantially the tensile strength of the original, untreated yarns.

Example 3 A woven viscose rayon fabric of/an 80 x 70 thread count, wassoaked for 90 seconds at 75 C. in a solution of 4% sulfuric acid and 3%periodic acid by weight. After washing and drying the acid treatedfabric, the same was dissolved in a 8% aqueous solution of sodiumhydroxide, showing a solubility of 97.9%. The acid treated fabricretained substantially its original texture and tensile strength. r

Example 4 A woven viscose rayon fabric of a 48 x 40 thread count, wassoaked for 90 seconds in a 4% aqueous solution of chromic acid at C. Theacid treated fabric retained its original form after washing and drying.

The acid treated fabric was then placed in an 8% aqueous solution ofsodium hydroxide at 35 C., for a half hour. Solution of the fabric tookplape to the extent of 98.4%.

Example 5 The procedure set forth in Example 1 was repeated except thatthe temperature of the sulfuric acid-sodium bichromate solution was 40C. The impregnating time was extended to 10 minutes. The acid treatedfabric was then washed and dried. The fabric was then dissolved in 10%sodium hydroxide, by weight, showing a solubility of 97.4% without agummy residue. The acid treated fabric retained substantially itsoriginal texture.

Example 6 A viscous rayon fabric was treated with 15 seconds with anaqueous solution containing by weight 10%;- concentrated sulfuric acidand 4%. sodium bichromate, at C. The acid treated fabric was then washedand dried 3. and then placed in a 10% aqueous solution of sodiumhydroxide at 90 C. The fabric dissolved to the extent of 98.7%.

Example 7 A Bemberg rayon fabric was treated for 90 seconds with anaqueous solution of 9% concentrated sulfuric acid and 4% sodiumbichromate, at 75 C. The acid treated fabric was washed and dried,showing the original texture and substantially the strength of theoriginal fabric. The treated fabric was then placed in an 8% aqueoussolution of sodium hydroxide at 30 C. for /2 hour. Solubility was 97.8%and there was no gummy residue.

Example 8 A cuprammonium rayon fabric was soaked for 5 seconds in anaqueous solution containing by weight 6% sodium bichromate and 12%concentrated sulfuric acid. The soaking took place at a temperature of75 C. The acid treated fabric was then washed and dried and then treatedwith a aqueous solution of sodium hydroxide at the boil. The treatedfabric dissolved to the extent of 98.9%. 1 The chromic acid or periodicacid treatment of the rayon, in fabric, yarn or nonwoven form, may bebased on aqueous solutions of such acids or combinations of reagentsforming the acid in situ. The acid treatment may be efiected attemperatures ranging from room temperature to boiling and with acidconcentrations varying by weight, from 0.5% to 50%. A preferred range ofacid concentrations is between 4% and 10%.

With higher acid concentrations, impregnation interval is reduced andmay be as little as a few seconds. The treating temperature is adjustedin inverse relation to acid concentration. Also, with relatively lowacid concentrations, the impregnation period is extended and may rangeup to hours.

It is understood that the acid treated fabric is washed with water insuitable washing tanks and dried with equipment known in the art.

In all cases, the conditions of acid treatment of the selected rayonfabric, yarn or thread, with chromic acid or periodic acid, is such asto leave the original physical form of the untreated fabric. Thus, thetensile strength of the treated fabric is substantially that of theoriginal fabric. Such acid treated fabric may be readily handled inreeling machines and lace making machines, as well as other textileequipment, as may be used in the manufacture of lace on an alkalinesolubilized backing.

The acid treated rayon in yarn form, may be incorporated in textilefabrics including conventional textile yarns which are not readilysoluble in alkaline solutions. The finished fabric is then treated in analkaline bath dissolving the alkaline soluble yarns, to thereby produceselected textile affects.

The term Rayon as used herein refers to regenerated cellulose having alower degree of polymerization then that of natural cellulose such ascotton, wood pulp and the like. Further such terminal includes rayonproduced by the xanthate process (viscose); cupramrnonium (Bemberg) andby saponification of cellulose acetate.

The acid treated rayon of the instant invention may be dissolved inalkaline solutions of a wide range of concentrations, being soluble inaqueous solutions of sodium hydroxide having a concentration of fromabout 0.1% to about 35.0%. It is understood that in lieu of sodiumhydroxide, other alkaline reagents may be used, including potassiumhydroxide, lithium hydroxide, sodium carbonate, trisodium phosphate andthe like.

I claim: i

1. The process of forming alkali soluble textile material withoutresorting to a carboxymethylation step which comprises impregnatingrayon with an aqueous solution of an acid selected from the groupconsisting of chromic acid and periodic acid under concentration, timeand temperature conditions sufiicient to obtain a modified textilematerial which retains the physical form and a major portion of thestrength of the untreated rayon and which is highly soluble in alkalinedissolving baths and free of gummy residues as an incident to thesolution thereof in said baths.

2. The process of Claim 1 wherein said acid is chromic acid.

3. The process of claim 2 wherein said acid has a concentration of from0.5% to 50.0%.

4. The process of Claim 3 wherein the time and temperature of the acidimpregnation is inversely related to the acid concentration.

5. Textile material produced by the process of Claim 1.

6. The process of Claim 1 wherein said rayon is viscose rayon.

7. The process of Claim 1 wherein said rayon is cuprammonium rayon.

8. The process of Claim 1 wherein said rayon is saponified celluloseacetate.

References Cited UNITED STATES PATENTS 2,921,934 1/1960 'Weisberg 8129 X3,493,319 2/1970 Berni et a1. 8120 3,385,653 5/1968 Whitfield et a18-420 X 2,938,765 5/1960 Reinhardt et al. 8F120 X RICHARD D. LOVERING,Primary Examiner

